Colorizing with hue adjustment

For a quick and dirty colorization of images, hue adjustment is your best friend. However, the danger with using hue adjustment is that you don't have much control over your tones compared to when you were using color curves.

To add the hue adjustment node in Blender's Node Editor Window, press SHIFT A then choose Color then finally Hue Saturation Value. This will add the Hue Saturation Value Node which is basically used to adjust the image's tint, saturation (grayscale, vibrant colors), and value (brightness). Later on in this article, you'll see just how useful this node will be. But for now, let's stick with just the hue adjustment aspect of this node.

Move the mouse over the image to enlarge it.

(Adding the Hue Saturation Value Node)

(Hue Saturation Value Node)

To colorize your images, simply slide the Hue slider. When using the hue slider, it's a good rule of thumb to keep the adjustments at a minimum, but for other special purpose, you can set them the way you want to. Below are some examples of different values of the Hue Adjustment.

High dynamic look

You often see this effect posted on photo blogs and websites where they take a regular photo and turn it into something more interesting, with colors popping out. In computer graphics and photography, they also call this technique High Dynamic Range Imaging (HDRi/HDR). HDR images represent a greater dynamic range of luminance between the lightest and darkest portions of an image. There are several techniques to achieve this in popular programs like Adobe Photoshop or GIMP. In photography, newer digital cameras have a post-processing capability to create such images by taking three photos of the same shot, one with a negative exposure value, one normal exposure, and the third one with a positive exposure value. It then combines all three into one photo creating this effect. Some higher model cameras even take it further by taking more values to the negative and positive scale, creating an even further deeper ranged image.

However, for simplification purposes, we'll only be trying to imitate the effect and look just like what you see below:

(High Dynamic Look Example)

Let's go ahead and learn how to do this. First, in the Node Editor Window, add an Image Node and locate the image, sequence, or movie you want to grade. Afterwards, add a Hue Saturation Value node and connect the image input and image output sockets accordingly (see screenshot below).

(Image Node and Hue Saturation Value Node Linked)

Next, bring the Saturation value all the way to zero (0). This will create a fully desaturated version of the image.

Filter Nodes are very handy nodes to have at your disposal everytime you're doing color grading. They make your images sharper, softer, and they even create outlines based on some selected presets. Change the Filter Type from Soften to Sobel and then make the Factor a value of 0.2. To see the results, add a viewer node.

(Changing the Filter Type to Sobel With a Value of 0.200)

Next, add a Color Curve Node and create a custom S-curve on the Contrast Channel.

(Creating a Custom S Contrast Curve)

This next step is one of the most crucial parts so make sure you do it the right way. Add a Mix Node (SHIFT A > Color > Mix). On the Mix Node, change the mix type to Overlay. Connect the original Image Node to the upper Image Socket of the Mix Node then connect the Color Curve Node's image output socket to the lower Image Socket of the Mix Node. This will blend the original image (with the original rgb color values) with the desaturated image that we just created using an overlay function.

(Mixing the Nodes using Overlay Mix Type)

To accentuate the mixing effect, let's add one more Mix Node with an Overlay Mix Type and connect the nodes as seen in the screenshot below.

(Adding Another Mix Node with Overlay Mix Type)

On this part of the grading process, we are already losing and clipping some dark areas of the image, making it unrecognizable, due to the overlay mixing that was done. To address this, let's add another Mix Node with the Mix Type and let's blend a little of the original image into the output of the Overlay Mix by changing the Factor to 0.2.

(Final Mixing)

And that's about it! Try changing the blend types and factor to create more interesting effects to your taste. Experiment!

If you've followed the steps above, here's what we should be getting:

(High Dynamic Graded Image)

Image sharpening

Image sharpening is one of the many aspects of color grading where, if done too much, could create disaster, but if done sufficiently, will create a fairly convincing output.

To sharpen up your images, you can directly link your images to a Filter Node with Sharpen type. I usually play my factor values between 0.1 and 0.2. Anything far beyond that would be overkill.

(Too Much Sharpening)

(Moderate Sharpening)

When done right, the Sharpen Filter can make your images look more convincing and they can even pop details into your scene, especially textures that were rather blurred by their mapping.

Color overlaying

Another quick and easy way of colorizing your images/videos is through a technique called as Color Overlaying (not sure if I'm just the one calling it such). This is fairly applicable when you are in so much rush that you don't have time to tinker anymore with other settings, and honestly speaking, with your boss or client breathing down your neck, this might just be your easy way to get it done.

To create a Color Overlay setup, first add an RGB Node (SHIFT A > Input > RGB). This will bring up a color wheel for you to select colors from. Alternatively, you can also click on the color bar to select colors better and input their values accordingly.

(Adding an RGB Node)

(The RGB Node)

Now, to colorize our input images/videos, we'll be adding a Mix Node, just like how we did in the previous topics. Check the screenshot below for the setup. The points to note here are: blend type, color (of course), and factor values. Quick and dirty but it gets the job done.

Toning up and toning down colors

A long time ago with Blender, toning up or down specific ranges of colors would take a lot of effort, and on some scenes even impossible due to the lack of tools. But with the advent of Blender 2.5, new tools and specific nodes arose, including the Hue Correct Node, for which I owe the Blender developers a lot. The Hue Correct Node is a powerful and useful tool.

(The Hue Correct Node)

What this node does is it takes a color value from your image, depending on what channel would be affected – hue, saturation, value, and it can either increase or decrease the value accordingly without affecting any other color. The default points to work on are 9 but you can simply add as you wish by clicking anywhere on the curve, which will give you finer control over how the colors are sampled.

To add this node, press SHIFT A, choose Color, then finally click on Hue Correct. By default, the Saturation Channel is active, but depending on the work you're doing, feel free to play around.

(Desaturating the Flower Petals)

(Saturating the Flower Petals)

(Desaturating the Leaves)

(Saturating the Leaves)

(Altering the Hue of the Leaves and the Petals)

Creating a sepia tone

Sepia Toning can either refer to a photographic technique of making images look as though they were older or it can refer to the treatment of making photographs look older and enhancing their archival qualities. But both relate more to the toning quality.

Sepia toned images look more brown than any other color. Some even look pale white due to the photograph's old age. There are no definite rules though in creating sepia-toned images, it just all comes down into how old you want to treat them.

The concept of sepia toning is similar to that of color overlaying. To do so, first add a Hue Saturation Value Node and connect it to the image you're applying sepia tone to.

(Hue Saturation Value Node Added)

Next step is to desaturate the image by moving the Saturation Slider to a lower value.

(Desaturating the Image)

Next, add an RGB Node. Then mix the desaturated image with the color output of the RGB node using an overlay mix filter. Adjust the Factor value accordingly, depending on your preference.

(Overlaying the Color and the Desaturated Image)

To add aging to the image without adding textures (which we'll discuss in the next part of this article), we'll add a slight blur to the image. To blur the image, press SHIFT A, choose Filter, then click on Blur.

(Adding a Blur Filter)

Change the Filter Type to Fast Gaussian, then change the x blur and y blur values as well. Just remember to keep them on a moderate level.

(Blurring the Image)

Then finally, mix the blurred output with the unblurred image, choosing from a variety of mix types depending on your choice.

(Mixing the Results)

Leading us to this final image:

(Sepia-toned Image)

Summary

In this article, we learned some more color grading techniques which includes: colorizing with hue adjustment, high dynamic look, image sharpening, color overlaying, toning up and toning down colors, and finally, creating a sepia tone.

For the next part, we'll discuss further how to achieve some stylization techniques involved with color grading and as a gift, I'll be providing BONUSES at the end of the article, so stay tuned! These topics are as follows:

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